Method for producing forms and foamed metal forms

ABSTRACT

The invention relates to the production of forms or similar from foamed metal based on aluminum or other metals. Semi-finished product bodies or similar consisting of a foamable semi-finished product material obtained by compacting a mixture of at least one matrix metal powder and at least one expanding agent which releases a foaming gas are placed into a foaming mould or similar where they are geometrically arranged in the desired manner and then heated to a temperature in the range of melting temperature of the matrix metal. Once the mould has been filled, the foaming process is concluded and the resulting foamed metal forms are shaped out. The invention is characterized in that at least one foamable compacted semi-finished product body is placed into a foaming mould together with at least one structure or functional part or similar consisting of a material which does not foam at the melting temperature of the matrix metal, retained in a desired position and then heated whereby metal foam is produced, said metal foam contact-binding or surrounding the structure or functional part in the form corresponding to the inner cavity of the mould. The metal of the metal foam formed is fully or partially brought into contact with the structure or functional part and after cooling, the composite form obtained is removed form the mould with the structure or functional part bonded in the metal foam.

The present invention relates generally to novel foamed metal moldings,and in particular to a novel process for the specific and reproducibleproduction of these novel moldings.

In recent years a large number of publications and patents have beenissued concerning the production of foamed metals, devices for carryingout the process and also concerning the metal/foaming agent mixturesrequired for foamed metal production or the semifinished products foruse in a metal foaming production process and concerning the productionof said semifinished product.

Reference is made only by way of example and by no means exhaustively tothe following documents with regard to the proposals and activitieswhich have become known in this area.

DE 1 164 102 A, DE 196 12 781 C1, DE 43 40 791A1, DE 44 26 627 A1, EP460 392 A1, EP588 182A2.

Reference is also to be made here to a known technique of foamingmetals, in which semifinished products formed from compacted metalparticle/foaming agent particle mixtures are placed in foaming molds,for example of steel, and made to expand by heating.

According to EP 804 982 A2, the powder-metallurgical starting materialis heated in a heated chamber outside a foam casting mold and made toexpand, after which the metal foam, adjusted in its amount to match thevolume capacity of the casting mold, is pressed in its entirety into thecasting mold, a relatively complex technique.

In U.S. Pat. No. 3,087,807 A there is a description of a processaccording to which a semifinished product, formed to correspondapproximately in its shape to the desired final form of the finishedfoamed metal body, is introduced into a hollow enclosure and expandedthere by heating.

DE 44 24 15 A1 describes foamed metals with anisotropic properties,which are produced by heating the foamable semifinished product in thefoaming and casting mold and subsequent deformation. It is stated therethat, for destroying the walls between the pores for the purpose offurther reducing their number, said walls representing the means bywhich the electrical and thermal conduction of the foamed metal, initself reduced by the pores, takes place, it is possible to provide forthe integration of small ceramic or hard-metal particles, short fibersor the like, which serve as crack starters during the deformation.

The number and variability of the application possibilities of foamedmetals or of moldings, workpieces, structural elements or the likeproduced from them is high. Mention is to be made at this point, just asexamples, of the stiffening of hollow forms, all structural elementsused for sound and vibration damping of the widest variety of types,also structural elements inhibiting energy flows, such as heat flow forexample, and not least use as decorative and covering structuralelements, increasingly valued on account of their low density, such asfor example wall plates and panels or the like, the foam structureitself, or else foam-structure limits within the structural elements,sometimes providing ist surface with attractive esthetic aspects, whichmay serve for decorative purposes.

In many cases, however, it is a fact that the individual foamed metalmolding by itself is not functional and, as for example in the case ofsoundproofing structural elements, wall panels or the like, requiressome sort of securing means or else, for example, is to have cavities,openings or the like, which are intended for example for receivingsecuring, connecting and/or joining elements.

It is consequently necessary after completion of the foamed metal bodyto perform finishing work on it, such that the required clearances aremade in it, such that, for example, retaining elements have to bescrewed into the previously made holes or that clamping andposition-retaining elements, for example reaching around the edges ofthe structural element, have to be attached.

If, for example, foamed metal composite structural elements are to berealized, that is to say for example sandwich structural elements, forexample with a lower and upper solid covering metal sheet and a foamedmetal structure in between, it has previously been the procedure tointroduce a metal powder/foaming-agent powder mixture between the twometal sheets and then produce an essentially compact preform orsemifinished body with outer covering layers, for example by rolling,pressing or the like, which body is expanded at elevated temperature,for example in a mold, the bottom sheet then for example remaining inposition and the covering sheet being “lifted” into a final position bythe expanding foamed metal. A disadvantage of this technology, citedhere as an example, is that it allows an exact final positioning of thesheets to be achieved only with difficulty.

The object of the invention is to provide a process in which there isessentially no longer any need, such as that described above, for thesubsequent provision of structural elements, retaining elements,cavities, clearances or the like. The novel process should, furthermore,save the use of costly-to-produce pre-material, such as for example thesemifinished product as described above, on the basis of a compactedmetal powder/foaming agent/covering metal sheet composite and shouldlead to foamed metal products with integrated-in or integrated-on solidelements with exactly controllable final positioning.

The novel process is finally intended to enable the production offinished foamed metal moldings and structural elements suitable rightaway for technical operation and use, in essentially a single processstep.

The invention consequently relates to a novel process for producingmoldings, workpieces or structural elements from or with foamed metal onthe basis of aluminum or aluminum alloys or other metals or alloys, inwhich process semifinished bodies, bars, profiles, plates or the like offoamable semifinished material, obtained by powder-metallurgical meansby compacting a mixture of at least one powder of the matrix metal withat least one foaming agent which releases a foaming gas at elevatedtemperature and is base d on at least one metal hydride or some otherfoaming agent, are introduced into a foaming and shaping mold or thelike, are arranged there in the respectively desired geometricalarrangement and two-dimensional and/or three-dimensional distribution,and are brought to a temperature in the range of the melting temperatureof the matrix metal in the said mold by heating, the foaming operationis ended after filling of the cavity of said mold to a desired degreewith the foamed metal formed and, finally, the foamed metal moldings,workpieces or structural elements obtained in this way are demolded orremoved, characterized therein, that

at least one foamable, compacted semifinished body or a plurality ofsemifinished bodies of this type is/are introduced into the foaming andshaping mold, together with at least one structure or body formed from amaterial or solid material or metal not foamable at the meltingtemperature of the matrix metal o r foaming temperature and/or a(technical) functional structural element from the group comprisingwires, cables, bars, networks, gratings, foils, plates, sheets,honeycomb bodies, profiles, tubes, bushes, anchoring elements, screwshanks or the like, and is/are held in the desired Position, after whichthe heating is performed with formation of the foamed metal, enclosingthe structure or the (solid) body and/or functional structural elementintegrally and snugly in the form or shape corresponding to the moldcavity,

the material or matrix metal of the foamed metal formed at therespective foaming temperature being brought into contact with theentire structure or (solid) body and/or functional structural element orwith a part of the same, and

after appropriate cooling, the composite molding or structural elementobtained, with a structure firmly bonded in the foamed metal, or firmlybonded (solid) body and/or functional structural element, is demolded.

Consequently, the essence of the invention is not only in particularthat the foaming operation serves for the forming of the foamed metalitself but also that the foamed metal which develops bonds in situ andintegrally with the solid parts, of whatever specific kind they are.Consequently, subsequent material weaknesses, for example due to makingholes, threads or the like for the fastening of functional parts,retaining elements or the like can be avoided and the bonding in andanchorage of the solid parts in the finished foamed metal body isachieved to an optimum extent by their in-situ encapsulation in foam.

The individual solid body or functional structural element to beaccommodated by the expanding foamed metal can, as expressed above, beentirely surrounded by the foam, whereby the (solid) insert(s) forexample provide for a modification of the foam structure. Reinforcingelements for example, such as bars, wires, networks or the like forexample, come into consideration for this. However, the foamed metal mayalso enclose only the anchoring region or the like of a functionalstructural element, for example a fastening element, the actualfunctional region extending for example above the surface of the foamedmetal body, protruding from it or the like. If metal sheets, that is tosay solid bodies with a planar or spatial, but predominantly flat extentare to be joined to the foamed metal, the foamed metal comes to bear ina flat, integrating manner and consequently is integrated flat onto themetal sheet.

A particularly intimate bond between the solid body or plurality ofsolid bodies and foamed metal can be achieved with a choice of materialaccording to the first embodiment of the invention.

As provided in the case of a second implementational variant of thisinvention, the individual (solid) body does not have to be producedcompletely from a metal compatible with the matrix metal of the foamedbody which is forming, but rather a coating of the same which promotesmaterial bonding may well suffice, although an integral bond of saidcoating with the basic body forming its substrate is important.

The invention further comprises as a third variant a selection ofmaterials, material phases, layers or the like coming into considerationfor the effective bonding of the (solid) parts into the foamed metalbody.

Likewise preferred special cases for the desired high degree ofintegration of the solid bodies or solid functional structural elementsinto the foamed metal are respectively shown by the fourth and fifthvariants.

In this sense, a number of metals or metal combinations promoting thematerial bond referred to and specifically directed at thealuminum-based foam matrix metals used to a great extent and withpreference are mentioned there as the last variant.

For cases where an intimate bond, as previously dealt with at length,between the foam and the body embedded in the same is not desired, oreven subsequent removal of the body is to take place, the measuresbrought together in the first implementational variant of the inventionmay bring advantages.

There are in fact no limits to the techniques for applying the coatingspromoting or else inhibiting the material bond between the matrix metaland the solid parts encapsulated in the foam of the same. Accordingly, anumber of such coating technologies that are particularly preferredwithin the scope of the invention are mentioned in the second variantaccording to the invention.

The material bond, in itself essential and desired for most cases, canbe supported in an advantageous way by measures for increasing themechanical bond between the foamed metal and individual solid bodies, asprovided for example by enlarging or specially shaping its surface, asprovided according to the third preferred embodiment of the invention.

The solid bodies to be integrated into the foam may be produced forexample by casting, continuous casting, extrusion molding, extrusion,rolling or the like. For certain cases, for example if the insertstructural elements are to meet particularly high technologicalrequirements, that is to say are to have, for example, a high level ofhardness, abrasion resistance, chemical resistance or the like, the useof solid bodies or structural elements of material produced bypowder-technological means and compacted, for example sintered, is alsopossible.

Molding or structural elements to be foam-encapsulated of materials withmelting temperatures which lie above the melting temperature of themetal of the basic body to be expanded are preferably used.

A major advantage of the novel process of in situ foaming is provided bythe first implementational variant specified in claim 5, which consistsin that the structures, bodies or functional structural elements to beintegrated onto or into the foam of the matrix metal are introduced intothe shaping mold together with foamable semifinished bodies, which haveessentially a geometry which is similar to the geometry of the finishedcomposite product obtained after foaming.

The disadvantages and problems occurring when, as described above andpreviously known, the semifinished product used is already in the formof a material composite when it is to be introduced and then expandedtogether with the solid elements, for example metal sheets, present inthe composite, concerning a specific positioning corresponding to thedesired final positioning in the finished composite foamed body, havealready being briefly discussed above. The process according to theinvention provides the major advantage here that it makes it possiblefor the first time for the solid parts actually to be finally positionedexactly at the desired locations of the foamed body, in a position whichis also exact in terms of the angular and spatial attitude, with aprocedure such as that provided according to the second embodiment ofclaim being of particular advantage.

The invention includes a first preferred process variant in which theretaining elements serving for an exact positioning of the solid partsas it were “go into” the foam matrix, or the like, in other words can begenuinely material-integrated into the same.

To avoid undesired shifting or slipping of the semifinished bodies withrespect to one another during the foaming operation, said bodiesthemselves indeed having to be arranged in the mold before the foamingprocess quite specifically and preferably in such a way that they matchthe final form, it has further proven to be particularly favorable tomake the semifinished bodies available for the foamed metal formationfor instance in the form of mats, bundles or the like held together bymetal wires or by filaments of material which is soluble in the matrixmetal or for example combustible with essentially no residue; see inthis respect the second variant of claim 6, it then just being necessaryto follow a procedure in which the mats can be cut to the appropriatelength and possibly also width, and the pieces of mat contoured in thisway can be introduced directly into the mold, whereby the risk of thesemifinished bodies shifting with respect to one another no longerexists. At locations of relatively great foam height, a correspondinglyshaped second mat may be arranged on the first mat, etc.

Retaining elements, whatever form they take, with a higher meltingtemperature than that of the matrix metal forming the foam arepreferred.

If it is intended to produce particularly robust sandwich foamed metalbodies with metal sheets or foils respectively bounding the foamed metalbodies above and below or on both sides, which lends the moldingparticularly high mechanical stability, it is favorable to arrange inthe foaming and shaping mold foils and/or metal sheets of this type atthe corresponding locations of the in the desired position. Thisprovides the advantage that, for example, an “upper” covering foil or acoverage sheet of this type is not arranged, as previously, directly onthe body of compacted metal matrix/foaming agent semifinished productarranged on the first sheet, this sheet or foil then being lifted by thefoamed metal itself, with increasing pore formation and pore volumeenlargement, during the development of the foam, and finally pressedagainst the top of the mold. Rather, this upper covering foil or uppercovering sheet is arranged right away such that it is in the proximity,of, or bears against, the top of the mold, for example by means ofappropriate foil holders, so that the aimed for welding with the foamedmetal reaching it during the foaming process takes place right away inthe desired, exact position.

To obtain a solid body/foamed metal composite molding that is virtuallyoptimum, requires a minimum of finishing effort and is in the final formand final dimension, the charging of the foaming and shaping moldadjusted to match the final form is particularly favorable. In the wayspecified there, integral foam structural elements of the novel typewith largely homogeneous pores can be achieved.

For the production of foamed-metal moldings having pore fractions, poredensities or pore volumes varying locally in regions of their volume,the type of mold charging with the bodies of the foamable semifinishedproduct provided according to the second variant of this claim bringsadvantages.

For achieving moldings with optimum bonding-in of the solid bodies, ithas proven to be particularly advantageous to maintain ratios betweenthe volumes or the total volume of the compacted, foamable semifinishedbodies introduced into the mold and the cavity of the shaping mold.

The invention is not in any way restricted to “full” solid bodies, butrather the incorporation of hollow solid bodies, that is to say bodieswhich are hollow but virtually solid surrounding walls, may also beprovided.

A further advantageous possibility consists in that foamed metal bodiesare created with clearances, cavities or the like which are accessiblefrom the outside or, for example, also pass through them, which on theone hand saves such empty spaces from subsequently being introduced, buton the other hand has the advantage that the hollow bodies forming thelimitation of the empty spaces there provide a significant mechanicalreinforcement together with the foamed metal surrounding and integratingthem. For example, straight tubular bodies from one wall to the oppositewall of the mold can be foam-encapsulated there tight or, for example,bent tubular bodies from one wall to a neighboring wall of the mold.

In order on the one hand to allow for as high a surface area as possiblefor the contact of the foamable compacted semifinished material with themold or mold base provided for heating up, shaping and dimensioning thelatter, and on the other hand to avoid undesired slipping oruncontrolled rolling away of the semifinished bodies during manipulationof the mold, and consequently irregular or undesired material densitydistribution in the mold before foaming, it is favorable according to athird variant of claim 9 to provide a semifinished material with bodieswith at least one flat or planar resting side, that is to say underside,by which these semifinished bodies rest on the mold base or a compositemetal sheet placed in said mold.

Finally, the invention relates to the composite foamed bodies producedby the novel process.

To sum up, the following is consequently to be stated:

As already mentioned, according to the invention a foamable semifinishedproduct obtained by powder-metallurgical production means is used. Thestarting product for the production of aluminum foam moldings is, forexample, a powder mixture of aluminum or an aluminum alloy,homogeneously mixed with a foaming agent—preferably titanium hydride—andpossibly further powder-like additives, which is compacted on acompacting installation, for example a CONFORM system, by pressing,extruding, rolling or in a comparable way, to form piece goods, that isto say bars, plates, profiles or similar semifinished forms, a densityof the semifinished product obtainable in this way which preferably liesabove approximately 95% of the theoretical density of the metal matrixusually being achieved.

There are known sandwich plates with covering metal sheets, foils or thelike applied on one or both sides which have been clad by roll-bondingin a first step, in order finally to join these covering sheetsmetallically to the metal matrix of the foamable semifinished product,possibly to contour this laminar structure and then, by heating to themelting temperature of the foamable semifinished product, form thefoamed body, which is then finally bonded with a material-integrally tothe metallic covering sheets; see in this respect, for example, DE 19612 781 C1.

The following are among the disadvantages of the previously knownprocesses:

a) The roll-bonding cladding just briefly described presupposes that thefoamable semifinished product is also available from the outset in plateor sheet form. Such sheet production by powder-metallurgical means isdifficult. Known technologies which are available are powder rolling,which however has not so far been successfully developed to theproduction stage in conjunction with an foamable semifinished product,along with extrusion molding. In extrusion molding, however, there arerelatively narrow limits to the profile width, determined by the insidewidth of the recipient. If an extrusion-molded profile is rolled in thelongitudinal direction, the widening of the same produced as a result isinconsiderable. If greater sheet widths are required, theextrusion-molded profile must be cut to length and then introducedtransversely into the rolling nip. The production of relatively largeamounts of composite plates by transverse rolling is usually rejected,however, by the rolling mills for safety reasons.

b) Structural elements with covering sheets applied on both sides may beeither smooth on both sides or they have, for example, contours whichare the same as one another on both sides.

c) On sandwich structural elements with covering sheets arranged on bothsides, which after roll-bonding cladding and before foaming have“angular” contours or cross sections, for example similar to a flat Uwith lugs protruding away at an angle on both sides, somewhat like this:, the part of the foamable semifinished product in the vertical positioncannot expand horizontally. The wall thickness of the foam core istherefore greater in the horizontal positions and less in the verticalpositions after expansion. The roll-bonding-clad semifinished product ofthis type, that is to say a sandwich composite, with contours, can beused only for limited geometries and sizes. With increasing thickness ofthe expanded structural element, the geometry of the lower and uppercovering sheets changes significantly. The semifinished product rolledin between the covering sheets cannot adapt to these changes.

A number of significant points and preferred variants of the processaccording to the invention are now globally summarized as follows:

1. Covering sheets and foamable semifinished bodies in bar, profile orsimilar form are placed adjacent to each other and one above each otherin a foaming and shaping mold.

2. An upper covering sheet to be integrally bonded to the foamed metal,and a lower covering sheet of this type, may have forms, cross-sectionalshapes or topographies which are different from one another without anyproblem.

3. Foamed sandwich plates can be produced by placing underlying andcovering sheets, foils or the like into the mold, without thepreparatory or intermediate step of roll-bonding cladding or compactingto form a composite semifinished product, that is to say virtually inone operation.

4. In the case of sandwich foamed metal sheets, the covering sheetsconsist for example of aluminum or other metals, such as for examplesteel, Ni-based alloys and their alloys, the melting point of which isfor example at least 50° C. above the melting point of the semifinishedproduct or matrix metal to be expanded.

5. The foamable semifinished product is preferably formed by profilesproduced in a “CONFORM” or extrusion-molding installation, preferablywith flat or round dimensions, the cross section of which can be adaptedoverall to the cavity of the mold in such a way that a plurality ofprofiles are placed adjacent to another or one above each other, theamount, degree of filling and filling height being governed by thedesired and aimed for density of the foamed metal structural elementrespectively to be produced.

6. Foamable semifinished bodies with the same dimensions can be used fordifferent structural elements and different densities and thicknesses.Locally different properties can be achieved in the finished structuralelement by arrangement of these semifinished inserts at locallydifferent proximities to one another. At the limits between thesemifinished bodies or profiles originally is placed into the mold,patterns are produced on the finished foamed metal body or on thesurface of the latter and can be used for decorative purposes.

7. To secure adjacent semifinished profiles in the mold against shiftingor slipping, it is favorable to use either profiles with at least oneflat resting surface, or else profiles or bars to be positioned adjacentto another, or else profiles or bars to be positioned next to oneanother are joined with the aid of thin metal wires or fibers of variousorigin, which for example burn without any residue—apart from gasformation—decompose or are dissolved in the molten foamed metal duringthe foaming operation, to form mats with, for example, uniform distancesbetween the bars, which mats may be prefabricated and precontoured—whichsignificantly simplifies the charging of the mold—when they are placedflat into the mold or locally in layers.

8. The profile cross section of the foamable semifinished product andthe position of the bodies to be formed within the mold isadvantageously chosen in such a way that the oxide skin located on thesurface of the semifinished bodies has sufficient space to break openduring the foaming operation, in which the semifinished product ofcourse is initially inflated, so that the nonoxidized metal of thefoamed body, liquid in this state, can bond metallically overall to formthe foamed body without troublesome oxide skins.

9. The original position of the semifinished bodies used can be seen onthe finished plate at its surface and the boundary surfaces between thesemifinished bodies, set off in their structure or appearance, can beused as a design element.

10. In the production of sandwich foamed metal plates or the like, thefoamed metal is diffusion-welded with a solid covering sheet, previouslynot yet heated up to the melting temperature, by the effect of the ismolten foam front. To improve the metallic bond between the foamed bodyand the covering sheet or the like, the covering sheet may be clad byrollbonding or coated either with a low-melting alloy, for exampleAISi₁₂, or with a diffusion-promoting agent, for example zinc. If anintimate bond between the foamed metal and the covering sheet is notdesired, release agents, such as for example graphite, an eloxal layeror the like, are favorably applied there.

11. According to an important production variant, the upper coveringsheet may be arranged such that it bears against the upper half or topof the mold, or for example is pressed against it, with the aid ofspacers or the like, or it is clamped onto it. It can consequently beensured that the upper covering sheet is already in its final positionduring the foaming operation and does not first have to be raised by thefront of the expanding foam and, as this happens, become for exampleincorrectly arranged, tilted or the like and is consequently not in thedesired final position in the finished foamed body.

Everything stated so far with respect to metal sheets appliesanalogously to all other forms of structural elements, structures, solidbodies and the like to be integrated into or onto the foamed metal.

An extremely wide variety of integral foam moldings can be produced bythe process described above:

i. Plates and sandwich plates which have covering sheets on one side ortwo sides or have no covering sheets, are plane-parallel or contouredand moldings with covering surface topographies differing from oneanother.

ii. Moldings of which the hollow interior is “stiffened” with foamedmetal.

iii. Upper and lower covering sheets ultimately joined to the foam maybe differently contoured, that is to say f or example on the upper sidethe foamed metal/solid-part composite body may have a corrugated-sheetcontour and on the underside it may, for example, be smooth or beprovided with a corrugated sheet of some other contour.

iv. By means of semifinished inserts of different densities and the sameor different dimensions from one another, different foam thicknesses canbe achieved with the same or constant density and (locally) differentdensities with (locally) different foam thicknesses.

v. For further weight savings, local clearances can be formed in a foamplate to be produced by means of inserts, for example with cavities,that is to say for example pieces of tube, between the covering sheets.

vi. Foamed bodies and end-plate sheets, foils or the like may optionallybe securely joined metallically to one another or optionally not bejoined to the foamed metal at all or joined in some locations.

vii. An extremely wide variety of solid metal parts, such as tubes andfastening elements, heat exchanging or cooling elements or the like, maybe incorporated into the foamed body during foaming.

viii. Foam plates, surrounded by edge strips or covering sheetsintegrated on one or both sides can be produced. In this case, theperipheral side edges may be formed for example with a channel, producedwith the aid of a two-part frame. After the foaming operation, thesurrounding frame is swung open and removed. A solid aluminum profile isjammed or adhesively bonded or screwed into the channel produced. Thesolid profile overlaps with its members the edge of the foam plate andconsequently allows a neat formation of the plate edge. Thissolid-profile frame may also be designed as a connecting piece of two ormore is plates joined together at the butt joint, whereby large-areaplate structures can also be produced.

A channel provided on the outer sides of the members of the solidaluminum profile can accommodate the edge of a covering sheet, which ispushed into the channel with its edge at right angles. The connectionbetween the covering sheet edge and the solid aluminum profile may beestablished by adhesive bonding or soldering, welding or else otherjoining techniques.

DETAILED DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail with reference to the drawing.

FIG. 1 shows particularly preferred forms of profiles of the foamablesemifinished product to be used, produced by compacting metal powder andfoaming-agent powder;

FIG. 2 shows the diagram of a mat formed with said semifinished bodiesand

FIG. 3 shows a diagram of a mold charged in a suitable way for carryingout the process according to the invention.

DETAILED DESCRIPTION

FIG. 1 shows in an oblique view three forms of foamable semifinishedbodies 60 to be used according to the invention which are particularlypreferred within the scope of the present invention, to be precise onewith a flat rectangular cross section, one with a more than semicircularcross section and one with a square cross section. At least one of theside faces, denoted in the drawings by 601, is essentially planar andflat, the other faces may have any shape, that is to say be for exampleconvexly curved or formed in some other way. An advantage of the planarfaces 601 is that the semifinished bodies 60 can bear with largesurface-area contact against the base of a mold or against a sandwichsheet fitted in said mold, the risk of locational displacement orslipping during movement or manipulation of the mold being significantlyreduced. A further major advantage is that an improvement in the heattransfer from the mold base into the semifinished product 60 is alsoachieved by this planar face 601.

FIG. 2 shows a further, particularly preferred possibility forpreventing undesired shifting of the semifinished bodies 60 both in themold and with respect to one another. It is shown in a sectional viewhow the semifinished bodies 60 have been woven, with here, too, a flatunderside 601, by means of filaments, wires 605 or the like, for exampleof the same material as the matrix metal to be foamed, to form a type ofmat 600, which contributes significantly to the stabilizing of thearrangement in the mold.

FIG. 3 shows in a diagrammatically schematic form an inner space 1112 ofa foaming and shaping mold 100 advantageously charged within the scopeof the invention: lying on the—here flat—mold base 11 is a lower solidbottom sheet 670 for the formation of a foamed metal/solid metalcomposite body, on which semifinished bodies 60 based onextrusion-molded compacts of a metal powder, for example Al powder, anda foaming-agent powder, for example TiH powder, are arranged with theirflat sides 601, then forming the matrix foamed metal when the foamingtemperature is reached. A curved composite sheet 671, which isultimately welded material-integrally with the matrix foamed metal 610expanding when the mold 100 is heated, is held in position against theconcavely curved top 12 of the mold by means of the supporting bodies620, supporting themselves from below, for example hollow cylinders orthe like, advantageously of a metal which can be solubilized from thefoamed metal or breaks up in it and melts at a somewhat highertemperature.

In order, for example, as FIG. 3 shows, to load a lower sandwich sheet670, arranged on the base of a mold 100, with the semifinished bodies60, all that is necessary, for example, is to cut to length or contourin each case flat pieces of the semifinished mat 600 explained above,shown in FIG. 2, and define the base area of the future foamed body withthem arranged, for example, against one another or else partly one abovethe other. The retaining wires 605 may be produced from metal compatiblewith the matrix metal or else from a material which burns, decomposes orcan be destroyed in some other way at the heating and foamingtemperature to be reached.

What is claimed is:
 1. A process for producing a molded shaped articlecomprising a foamed metal body having at least one non-foamablefunctional structural element embedded in the foamed body, comprisingthe steps of: (a) providing a hollow mold; (b) placing in the hollowmold (1) a foamable material comprising a metal and a foaming agent and(2) a functional structural element; (c) heating the mold to atemperature sufficient to foam the foamable material so that it expandsand fills the hollow mold; (d) cooling the mold; and (e) demolding theshaped article comprising a foamed metal body having at least onefunctional structural element embedded therein.
 2. A process accordingto claim 1, wherein the hollow mold defines an internal surface and theprocess further includes the steps of: (a) locating and supporting atleast one non-foamable functional structural element on the internalsurface of the mold with consumable retaining elements; and (b)consuming the retaining elements during the heating of the mold.